Platen.



No. 895,577. PATBNTEDAUG. 11, 190s. H. H. MOINTIRB.

PLATBN.

APPLICATION FILED HAY 9,1904.

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lto a- HERVEY H. MeiNTiRE, or soU'rH BEND, iNDiANA. v

PLATEN.

Specification o! Lettera Patent.

Patented Aug. v11, 190s.

V Application filed May 9, 1904. Serial No. 207,115'.

To all 'whom 'it' may concern:

Be it known that I, HERVEY H. MCINTIRE, citizen of the United States, residing at South Bend, in the county of St. Joseph and State of Indiana, have invented certain new and useful Im rovements in Flatens andl do hereby dec are the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in platens, and while more especially adapted for a hotographic printing machine, it is applica le to other Amachines em loying. a platen, or it may be hand operate and used independently of the machine.

The object of the present invention is to provide a platen which insures a yielding pressure on the ne ative, and consequently a perfect contact o? the photographic paper therewith.

With the above/object in view, the invention consists in providing a platen with a pneumatic elastic cushion, which, when iniiated and thecontact made, is caused' to assume a diiierentcontour by virtue of the elastic nature of the cushion and the ressure thereon; and which is provided wit means for compensating for this change in contact, whereby the actual resistance, occasioned by the shifting of air in the cushion, is maintained and a perfect or evenly distributed pressure on the photographic paper accomplished.

For a full understanding of the merits and advantages of my invention, reference is to be had to the following description and theV yaccompanying drawings wherein:

Figure 1 is a plan view of a platen embody\ ing my invention; Fig. 2 is a longitudinal vertical section of the same on the line a; :1: of Fig. 1, with the table or face board in which the negative is mounted shown in section beneath the platen 5 and, Fig. 3 is a similar view showing 'the position of the parts when the platen has been pressed into engagement with the paper and the negative.

Making renewed reference to the drawings, wherein similar characters of notation indicate corresponding parts appearing in the several illustrations and reference being had thereto, 1 desi natesia rectangular frame to the to of whic is secured a plate or cover 2,

rovi ed.with transverse apertures 3, and having secured near the sides thereof upon its upper face apair of plate s rings 4, the freeends ofA which overlap t e apertures which are located near the opposite ends of the late 2.

ounted inthe frame and size to close the lower side t ereof is a folpreferably of a lower 5, which is inclosed by the frame 1, and

from itsup er face extend pins 6 which are of such lengt as to project through the apertures 3 in theplate 2, with their u er ends in engagement with the free ends o yt y e plate springs, the plate sprin s being flat against t e p ate or cover and c osing the apertures therein when the follower is in its normal position which is flush with the lower faces of the frame.

Secured to the frame in any suitable manner as by cement or the like is an elastic airproof sack 7 from which extends a tube 8 that pierces the late 2 with its upper end projectin above t e same. This tube 8 may contain the usual valve for inflation, such as is commonly used in pneumatic tires, and when the elastic sack 7 is inil'ated with air, it forms a pneumatic cushion, which may be hereinafter designated as 9.

The neumatic cushion normally has the sha e s own in Fig. 2 with the contact face 10`t ereof convex and the u er wall thereof lightly bearing againstthe fbllower 5, which is loose or free with respect to said cushion, but which is operated u on by the cushion to move up and down within the frame, as will be fully ex lained hereinafter.

The tab e or face board of a photogra hic printing ap aratus is indicated at 11, an the negative w ich is mounted in an opening therein, is shown at 12.while 13 may indicate the photo raphic paper or sensitized element on whic the picture is to be printed. It being premised that a source of light is contained within a case and emitted on the negative from the side opposite to that upon which the photographic paper is placed, and pressure is brou ht to bear by bringing the contact face of t ecushion into engagement with the rint paper on the negative, as shownin Fig. 3; the compression of the air in the cushion is equal to the resistance offered by the sprin s 4, which are engaged by the ins 6 of the follower 5 and the normal ten ency of which is to s ring down ilat upon the cover-plate and hol the follower toward the cushion 9. Howevenwhen excess pressure is brought to bear u on the cushion, the shifting of the air therein changes the contoui thereof and causes its upper wall to stretch and force the follower u wardly against the action of the springs hecompression of the iiuid in the cushion creates a tension on the Walls thereof and particularly the up er rear wall, which woul lordinaril burst i it were not for the spring pressed fo lower which yields to the excess pressure. Furthermore, if some portion of the wall of the cushion were not permitted to yield to the excess pressure, there would be such a pressure upon the sensitized element and the negative as to injure the same and defeat the result accomplished by the piesent invcn tion, which is to maintain a uniform pressure and a perfect contact for the sensitized element. It is ap arent that in the case of an automatic mac ine where the laten is raised and lowered alternately, t e action and downward ressure of the laten would at all times be t e same; and it eing impossible to prevent the escape of air in a cushion of this character, owing to the leakage through the valve or otherwise, the constant pressure furnished b the springs 4 will comensate for such lea age and for the chan e in contour of the cushion, and thereby esta lish a perfect contact of the print paper. In view of this difficulty of maintaining an equal pressure of air in the cushion, the advantages of providing the spring pressed follower to compensate for the eakage and for the changing in contour of the cushion in making a contact, is apparent. Thus in this invention, the quantity of air in the cushion may vary considerably, yet the pressure would always be sufficient as the actual resistance is furnished by the springs, while the air simply forms a cushion.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is i 1. A platen provided with a pneumatic cushion, and means operating to permit the shifting of the excess air to a point to the rear of the normal backing ofthe cushion when under pressure.

2. A platen having a pneumatic cushion, and means operating to relieve the cushion of excess pressure when under compression and to automatically return the cushion lto its normal contour.

3. A platen provided with a pneumatic cushion, and means operating to automatically permit the shifting of the excess air of the cushion to a point to the rear of its normal position when under compression and without reducingr the normal air pressure.

4. A platen provided with a pneumatic cushion, and compensating means for shifting the excess air pressure and returning the same under approximately normal pressure without diminishing the supply.

5. A platen provided with a backing element, a pneumatic cushion, and means operating to permit the excess air to be automatically shifted to a position to the rear of the backing element.

6. A platen provided with a pneumatic cushion, and yielding means operating to permit the excess air to be automatically shifted to a position beyond the backing element.

7. A platen provided with a backing element, a pneumatic cushion, yieldable means between said cushion and backing element and operating to permit the excess pressure to be shifted beyond the normal position of the cushion.

8. A platen embodying a rectangular frame, a pneumatic cushion secured thereto, a cover plate for the frame having openings, springs secured to the cover plate and normally covering the openings, and a follower mounted in the frame between the cushion and the cover plate and having pins piercing said openings and arranged to engage with the springs.

9. A platen provided with a hollow backing element, a pneumatic cushion carried by said backing element, and yieldable means within said backing element and bearing against the cushion and o erating to permit the excess pressure to be s iifted to a position within the backing element.

l0. A platen provided with a hollow back-- ing element, a pneumatic cushion carried by said backing element,'and a spring pressed device Within said backing element and bearing upon said -cushion.

In testimony whereof I affix my signature, 1n presence of two witnesses.

HERVEY H. MCINTIRE.

Witnesses:

GEORGE OL'rsoH, ORALE HEss. 

